A lead or brass head hammer is ideal. Copper too but the expense is not necessary. Although I have brass hammers I prefer to use a dead blow with a firm non marring face. You want the sharp impact of the hammer to break the taper free. IMO anything softer requires more energy striking & is wasted energy. But you don't want the hammer face too hard where the repeated strikes over time will cause damage to the draw bar.Is the plastic dead blow satisfactory?
I have been trying to figure out what weight brass hammer to get...I think I see more more greenbacks ready to take flight
You could always make one ...